Hydraulically adjustable supporting device



Jan. 22, 1957 I M. D. SANDS 2,778,627

HYDRAULICALLY ADJUSTABLE SUPPORTING DEVICE Filed Feb. 16, 1954 F t m s s 6 2/ I}. /a j:/- H

INVENTOR. @455 3 jk/ms United States pat-6m,

HYDRAULICALLY ADJUSTABLE SUPPORTING DEVICE This invention relates to a hydraulically adjustable supporting device for any use where it is desired to resiliently support anything at an adjustable height. H is more particularly designed to provide an adjustable, resilient, seat support for the driver of a truck or bus. Such seats must be adjustable to comfortably accommodate various drivers. The usual drivers seat supports are either fixed or difiicult to adjust for height and do not provide resiliency to absorb road shocks.

The principal object of this invention is to provide a support for seats and other devices which can be quickly and easily raised or lowered to provide any desired seat height, and which, when set in'the desired adjusted position, will actto resiliently support the seat,

Another object of the invention is to so construct the device that all adjustments can be quickly and easily accomplished with-out the use of tools and to provide a device in which air will serve as the'cushioning medium plicity, economy, and efliciency. These will become more apparent from the following description.

In the following detailed description-of the invention,

7 reference is had to the accompanying drawing which forms a part hereof. Like numerals refer to like parts in all views of the drawing and throughout the description.

In the drawing:

Fig. 1 illustrates the improved adjustable resilient supporting device as it would appear applied to a conventional bus or truck drivers seat;

Fig. 2 is an enlarged, vertical section, taken on the line 22, Fig. 1, with the seat removed; and

Fig. 3 is a horizontal cross-section looking downwardly on the line 33, Fig. 2. r

In Fig. 1 a conventional seat bottom is indicated at 10, with its cushion at 11, and back rest at 12,. While the invention is illustrated and described as supporting the seat bottom 10, it is to be understood that it could be used for any supporting purpose where vertical adjustment and resiliency are desired.

The improved support employs a base plate 14 provided with suitable anchoring openings 15 by means of which it may be secured to a floor or other supporting surface by means of suitable anchor screws or bolts 16. The base plate 14 supports a cylindrical reservoir casing 17. The casing is closed at its top and bottom and is provided with a peripheral base flange 18 through which suitable cap screws 19 extend to secure the reservoir casing to the base plate 14.

A pressure cylinder 20 is formed concentrically Within the casing 17 and opens through the bottom thereof. The bottom of the pressure cylinder is sealed by the base plate 14, a suitable sealing gasket 21 being positioned between the flange 18 and the base plate 14. The pressure cylinder 20 extends upwardly through the top of the reservoir casing 17 and projects upwardly therefrom, terminating in an annular, threaded gasket ring 22.

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A cylindrical spacing sleeve 23, formed with an externally projecting shoulder or supporting flange 24, is secured in the upper extremity of the cylinder 20 by means of the ring 22. The ring 22 clamps a sealing gasket 25 against the top of the cylinder 20 and the top of the sleeve 23. j

A tubular plunger 26 extends downwardly through the gasket 25 and through the sleeve 23 and projects below the latter into the cylinder 20. The lower extremity of the plunger 26 is threaded as shown at 28 to carry an annular hydraulic piston 27. The piston 27 is provided with suitable sealing rings 29 to seal against the internal wall of the cylinder 20. It will be noted that the internal diameter of the plunger is relatively smaller than the: internal diameter of the pressure cylinder due in part to the spacing sleeve 23.

The piston 27 acts to clamp a flanged valve cage 39 and a valve plate 31 against the bottom of the plunger 26. The valve plate is provided with a central port 32 adapted to be closed by a valve disc 33 which is constantly urged into closed engagement with the port 32 by'means of a suitable valve spring 34 within the cage 30 The valve disc is provided with a concentric by-pass port 49 and the sides of the cage 30 are perforated to provide a plurality of fluid passages 35.

A floating piston 36 is slidably mounted in the tubular plunger 26 and is hermetically sealed to the inner wall of the plunger 26 by means of an upper cup washer 37 and a lower cup washer 38. The cup washers are clamped to the upper and lower fa-ces'of the floating piston 36 by means of an axial clamp bolt 39 extending through and between washer plates 40 resting against the cup washers 37 and 38. Additional sealing may be provided by means "of an external ring groove and O-ring 41.

A compression spring 42 is positioned between the head plate 43 of the plunger 26 and the floating piston 36 and acts to constantly urge the. latter downwardly in the plunger 26. g

A fluid passage 44 communicates between the reservoir casing 17 and the bottom of the cylinder 20. A threaded needle valve 45 extends from the exterior of the casing 17 through a threaded bushing 46 in alignment with the passage 44 to seal the latter when desired. The needle valve may be provided with any suitable turning device, such as a knurled finger button 47.

When the improved support is being assembled and before the base plate is bolted in place, it is inverted and rested upon the head plate 43 so as to be in its completely collapsed position. Hydraulic fluid 50 is now poured into the inverted open bottom of the cylinder 20 to completely fill the lower portion of the plunger 26, the cage 30, the piston 27 and the lower portion of the cylinder 20 so as to eliminate all air therefrom. The spring 42 will have forced the floating piston toward the valve cage 30 until the bolt 39 rests thereon.

The base plate is now bolted in sealing position, the valve 45 is closed and the entire device is righted to its upright position. The bushing 46 and the valve 45 are now removed and the reservoir casing is substantially filled with hydraulic fluid through the bushing opening. The bus-hing is then replaced and the device is ready for installation.

Let us assume the device has been properly installed and that it is desired to elevate the seat plate 43 to a desired elevation for use. The valve 45 is opened and the head plate 43 is lifted manually to the desired height. As the hydraulic piston 72 moves upwardly, fluid will be drawn from the reservoir casing through the passage 44- into the bottom of the cylinder 20. When the desired height has been reached, the valve 45 is closed to prevent the return of fluid to the reservoir and the fluid in the cylinder will act as a fixed support for the floating piston 36' and the latter will support the seat plate 43 on a cushion of'aircontained in the topof the plunger 26.

If weight, such as that of the vehicle driver, is now brought to bear on the plate 43, it will tend to force the plunger '26 downwardly in the cylinder 20 displacing hydraulicfluid therefrom. The displaced fluid will flow through the intake port 32 into the bottomof the plunger 26 below thepis'ton 36. Since the diameter of the cylinder 20 is greater than the diameter of the plunger, the fluid will tend to reach a greater height in the plunger. In tending to reach this greater height, it will lift the floating piston 36 so as to rapidly increase the pressure of the air in the plunger so as to resiliently resist the downward movement of the plate 43 and maintain the latter 'at substantially the preset height.

Now, let us assume the vehicle is moving and suddenly encounters a dip in the road. This causes the base plate 1'4 to *move away "from the hydraulic piston 27 increasing the displacement in the cylinder, causing fluid to flow relatively slowly through the by-pass port 49 to allow the floating piston to descend to relieve the pressure in the top of the plunger, allowing the air therein to expand to maintain the seat plate at substantially its original height setting.

Should the vehicle strike a sudden rise, the base plate 14 will be fonced toward the hydraulic piston 27, displacing fluid rapidly into the bottom of the plunger both around and through the valve disc 31 to rapidly lift the floating piston and increase the pressure in the upper portion of the plunger to absorb the shock.

Thus, it can be seen that the seat plate and its load will lac-maintained on a smooth, substantially level plane regardless of rapid vertical movements of the floor and base plate 14. It can also be seen that the height of the seat plate 43 is determined by the amount of fluid in the cylinder 20 and that a similar cushioning effect is always provided, regardless of the height of the seat plate, by the air compressed above the piston 36. A breather opening'51 may be formed in the top of the reservoir casing to maintain the air in the top of the casing at atmospheric pressure during fluctuations of the fluid level therein.

While a specific form of the improvement has been described and illustrated herein, it is desired to be under- 4 stood that the same may be varied, within the scope of the appended claims, without departing from the spirit of the invention.

Having thus described the invention, what is claimed and desired secured by Letters Patent is:

l. A hydraulically adjustable supporting device comprising: a vertically positioned pressure cylinder; a tubular plunger mounted to move vertically in said pressure cylinder and projecting above the top of the latter; a closed bottom in said cylinder; means for sealing the lower extremity of said plunger to said pressure cylinder; a floating piston mounted for vertical reciprocation in said plunger; a closed top in said tubular plunger; a reservoir casing surrounding said cylinder in spaced relation thereto; a fluid passage communicating between said reservoir casing and said cylinder; hydraulic fluid con-i tained in said cylinder and in said tubular plunger below! the floating piston therein to support the latter; and manually controlled valve meansin said passage which, when opened, allows said plunger to be lifted to draw fluid from said reservoir to said cylinder, and, when closed, prevents flow from said cylinder to said reservoir casing so that said floating piston will be supported at a desired height.

2. A hydraulically adjustable supporting device'as described in claim 1 having a spring interposed in said plunger between the closed top thereof and said floating piston and acting to resiliently support said plunger from said piston.

References Cited in the file of this patent UNITED STATES PATENTS Great Britain June 19, 1945 

